Rate of Sea Level Rise Doubled over 30 Years, New Study Shows

The question: How does new data provide a more refined look at global sea level trends over the past three decades, and how can it be used for future action?

The answer: Recent findings show that over the past 30 years, the rate of global sea level rise doubled. This rate measures the average rise in sea level each year—most of it resulting from climate change. The study found that in 1993, the rate was about 0.08 inches (2.1 millimeters) per year but has since increased to about 0.18 inches (4.5 millimeters) per year in 2023.

The study reports that sea level also is expected to grow by another 6.6 inches (169 millimeters) globally over the next 30 years if it follows this trend. This number is consistent with sea level projections from middle-of-the-road future warming scenarios in the IPCC’s Sixth Assessment Report. While the IPCC report created projections based on models driven by factors like population growth, economic trends, and climate policy, the newest study focuses on past satellite observations.

“We’ve had this succession of satellite missions over the past three decades, one building on top of another, and it’s that data on a global scale that allows us to precisely track the rate of global sea level rise,” said NASA Sea Level Change Team Principal Investigator Benjamin Hamlington, the new study’s lead author.

Although a number of factors contribute to sea level rise, the primary causes are warming and ice-melt due to greenhouse gas emissions, Hamlington said.

“It’s the heat being absorbed by the ocean, and then the ocean expands in response, and it’s the melting of the ice sheets and the glaciers that are in the mountains,” he said. “Having clarity on those two drivers and seeing that acceleration tells us a lot about how the climate system is responding globally to the increased heat being trapped by the atmosphere.”

Why it’s important: Sea level is on track to rise even more in the near future, and the new data allows scientists to better pinpoint specific causes that will drive rates of sea level change across the globe.

“We’re using our solid observations to understand what happens on a global scale, not just the global average, but how every location on Earth is responding and feeling the effects of sea level rise,” said Hamlington. “It allows us to be more certain about what might be changing the coast of the U.S. and off the coast of an island in the Pacific.”